In general, substrate processing equipment is classified into single wafer type substrate processing equipment capable of processing one substrate at a time and batch type substrate processing equipment capable of processing a plurality of substrates at the same time. The single wafer type substrate processing equipment has a simple structure, but has low productivity. Thus, the batch type substrate processing equipment capable of being mass-producing substrates is being widely used.
The batch type substrate processing equipment includes a processing chamber in which substrates horizontally stacked in multistage are accommodated and processed, a processing gas supply nozzle for supplying a processing gas into the processing chamber, and an exhaust line through which a gas in the processing chamber is exhausted. A substrate processing process using the batch type substrate processing equipment may be performed as follows. First, a plurality of substrates are loaded in the processing chamber. Then, while a gas within the processing chamber is exhausted through the exhaust line, a processing gas is supplied into the processing chamber through the processing gas supply nozzle. Here, the processing gas injected from the processing gas supply nozzle is introduced into the exhaust line through an exhaust hole while passing between the substrates to form a thin film on each of the substrates.
However, in the substrate processing apparatus according to the related art, the processing gas injected from the supply nozzle is introduced to the exhaust hole without being uniformly distributed on the substrate. That is, the processing gas passing through a central portion of the substrate flows slowly, and the processing gas passing through an outer portion of the substrate flows fast. Thus, a difference in film thickness between the thin film on the central portion of the substrate and the thin film on the outer portion of the substrate may occur to deteriorate quality of the substrate or the thin film on the substrate.